1. Field of the Invention
Internal combustion engines operate under a wide range of temperatures including low-temperature stop-and-go service as well as high temperature conditions produced by continuous high speed driving. Stop-and-go driving, particularly during cold, damp weather conditions leads to the formation of a sludge in the crankcase and in the oil passages of a gasoline or a diesel engine. This sludge seriously limits the ability of the crankcase oil to lubricate the engine. In addition, the sludge with its entrapped water tends to contribute to rust formation in the engine. The noted problems tend to be compounded by standard lubrication service recommendations for extended oil drain intervals.
It is known to employ nitrogen-containing dispersants and/or detergents in the formulation of crankcase lubricating oil compositions. Many of the known dispersant/detergent compounds are based on the reaction of an alkenylsuccinic acid or anhydride with an amine or polyamine to produce an alkylsuccinimide or an alkenylsuccinamic acid as determined by selected conditions of reaction.
It is also known to chlorinate alkenylsuccinic acid or anhydride prior to the reaction with an amine or polyamine in order to produce a reaction product in which a portion of the amine or polyamine is attached directly to the alkenyl radical of the alkenylsuccinic acid or anhydride. The thrust of many of these processes is to produce a product having a relatively high level of nitrogen in order to provide dispersancy in a lubricating oil composition.
With the introduction of smaller internal combustion engines which must operate at high speeds to produce the required torque output, it has become increasingly difficult to provide a satisfactory dispersant lubricating oil composition.
Another problem facing the industry is that of lubricating small diesel engines which have become increasingly popular for powering passenger motor vehicles. Diesel or compression ignition engines put new levels of lubrication and dispersant requirements on the crankcase lubricant and these needs are not satisfactorily met by conventional motor oils.
It is an object of this invention to provide a novel lubricating oil additive.
Another object is to provide a method for preparing a novel lubricating oil composition.
A further object is to provide a lubricating oil composition having improved dispersant properties for spark ignited and compression ignited internal combustion engines.
2. Description of the Prior Art
U.S. Pat. No. 3,172,892 discloses an alkenylsuccinimide formed from the reaction of an alkenylsuccinic anhydride and an alkylene polyamine and its use as a dispersant in a lubricating oil composition.
Netherlands Pat. No. 7,509,289 discloses the reaction product of an alkenylsuccinic anhydride and an aminoalcohol, namely a tris(hydroxymethyl)-aminomethane.